why is algebra so hard. why do we have to know this stuff ok well what is -15+x=5
Many situations in everyday life, plus many in job situations, require knowledge of algebra. The state of Michigan requires two years of algebra for all high school graduates.
-15+x=5
You need to get the unknown on one side of the equation, and the known numbers on the other side.
Add 15 to both sides.
x = 5 + 15
x = 20