2x+y=90
10x-4y=90
tell me how to do it so i can remember

So eliminate the y's
multiply first equatoin by 4 and add to 2nd eqution
8x+4y=360
10x-4y=90 +
18x+0y=450

18x=450
divide both sides by 18
x=25
sub back

2x+y=90
2(25)+y=90
50+y=90
minus 50
y=40

(x,y)
(25,40) is thea nswer

1. isolate the variable, in this case, d. subtract 35.5 on both sides of the equation.2. 52 subtracted by 35.5 is 16.53. therefore your answer would be d= 16.5this is the basics of pre algebra, isolating variable through adding, subtracting, multiplying, and dividing, if you have any other questions to ask just comment!