For x = ay - bz:
Add bz to both sides:
ay = x + bz
Divide a on both sides:
y = (x + bz)/a
For xy + yz = 10:
Distribute y from the left side:
y * (x + z) = 10
Divide by x + z:
y = 10/(x + z)
For (ab - ac)/z = x:
Multiply by z on both sides:
ab - ac = xz
Take out a from the left side:
a * (b - c) = xz
Divide by b - c on both sides:
a = xz/(b - c)
She needs a score of 89 for it to be an average of 91.00
Good night :). Sleep tight!
Answer: 20%
Step-by-step explanation: 3/15 = 1/5 = .20 = 20%
