D=number of dimes
q=number of quarters
let's count everything in cents
dimes are worth 10 cents
quarters are worth 25 cents
10d+25q=700
divide both sides by 5
2d+5q=140
he has 7 more quarters than dimes
q=7+d
subsitute 7+d for q in other equation
2d+5q=140
2d+5(7+d)=140
2d+35+5d=140
7d+35=140
minus 35 both sides
7d=105
divide both sides by 7
d=15
sub back
q=7+d
q=7+15
q=22
22 quarters and 15 dimes
Use the trapezium formula 1/2( sum of parallel lines)( height )
If I'm interpreting this right, it's -36 since a half times ten is 5... so it comes down to 5-41 which equals -36.
-4x-2y = 16
2y = -4x-16
Get one variable alone on both equations
-4x - 16 = 2y
-4x - 16 = 2y
You'll realize that they're the same equation.
Use substitution
-4x-16 = -4x-16
0 = 0
x = all solutions
Use x = all solutions in an earlier equation to find y
-4x - 16 = 2y
SInce x can be all solutions y is also all solutions
y = all solutions
