Answer:
7. 36 8. 1 9. 21
Step-by-step explanation:
You plug in the variables in the equation.
7.
8. 
9. 
Answer:
a 3² +4² = 25 the factors are 5²
b 8²+6²= 100 the factors are 5²and 2²
c 12²+5²= 169 the factors are 13²
d 8²+15²= 289 the factors are 17²
1: Solve for either x or y in one of the equations. So x + y = -1 is y = -x -1
2: substitute the new equation in the opposite equation. So x - (-x - 1) = 7
3: distribute the negative. X + x + 1 = 7
4: combine like terms. 2x + 1 = 7
5: solve for x. Subtract 1 on both sides. 2x = 6
6: divide by 2 to get x by itself. X = 3
7: plug the new value of x into one of the ORIGINAL equations. 3 + y = -1
8: solve for y. Subtract 3 on both sides.
Y = -4
9: the solution is written as (x,y) so the solution would be (3, -4)
B. Every third student entering the school in the morning
