What must $t$t equal to make the following equation true?
$1+t=4$1+t=4
What must $k$k equal to make the following equation true?
$k+1=7$k+1=7
What must $x$x equal to make the following equation true?
$6+x=13$6+x=13
What must $j$j equal to make the following equation true?
$j+5=10$j+5=10