7.04 Story problems with addition and subtraction

Start by performing the subtraction first then the addition using vertical algorithms.

To subtract 2.609 from 4.095 we write it in a vertical algorithm.

\begin{array}{c} &&4&.&0&9&5 \\ - &&2&.&6&0&9 \\ \hline \\ \hline \end{array}

Subtract the values down each column, regrouping where necessary.

\begin{array}{c} &&3&.&{}^10&8&{}^15 \\ - &&2&.&6&0&9 \\ \hline &&1&.&4&8&6 \\ \hline \end{array}

Now that we have found 4.095-2.609, we can add 2.27 to our answer.

Write it in a vertical algorithm. Use 0 as placeholder.

\begin{array}{c} &&1&.&4&8&6 \\ + &&2&.&2&7&0 \\ \hline \\ \hline \end{array}

Add the values down each column, regrouping where necessary.

\begin{array}{c} &&1&.&{}^14&8&6 \\ + &&2&.&2&7&0 \\ \hline &&3&.&7&5&6\\ \hline \end{array}

Add the distances Ned ran on Wednesday and Friday using a vertical algorithm.

Write it in a vertical algorithm.

\begin{array}{c} &&3&.&4 \\ + &&7&.&9 \\ \hline \\ \hline \end{array}

Add the values down each column, regrouping where necessary.

\begin{array}{c} &&{}^13&.&4 \\ + &&7&.&9 \\ \hline &1&1&.&3\\ \hline \end{array}

The total distance Ned ran before Saturday is 11.3 km.

Add the mass of the two rocks using a vertical algortihm.

Write it in a vertical algorithm.

\begin{array}{c} &&6&9&.&2&2 \\ + &&7&2&.&7&4 \\ \hline \\ \hline \end{array}

Add the values down each column, regrouping where necessary.

\begin{array}{c} &&{}^16&9&.&2&2 \\ + &&7&2&.&7&4 \\ \hline &1&4&1&.&9&6\\ \hline \end{array}

The total mass of the two rocks is 141.96 kg.

Subtract the cost of the mandarin from the amount Susana paid.

Write the subtraction in a vertical algorithm. Use 0 for placeholders.

\begin{array}{c} &&5&.&0&0 \\ - &&1&.&5&0 \\ \hline \\ \hline \end{array}

In the tenths column, 0 is less than 5, so we will trade 1 from the units column which leaves us with 4 and carry it over to the tenths column which gives us 10. Now we can subtract down each column.

\begin{array}{c} &&4&.&{}^10&0 \\ - &&1&.&5&0 \\ \hline &&3&.&5&0\\ \hline \end{array}

The change that Susana will receive is \$3.50.