Question

I need someone to solve this

Answer 1

Answer:

?? = 900

Step-by-step explanation:

Solve algebraically

let x be ball and y be cube

x + y = 100

x - y = 80

xy = ??

We can solve by elimination. Eliminate one of the variables by adding OR subtracting the entire equations. I will add.

.     x + y = 100

+    x - y = 80       y + - y = y - y = 0; The variable is eliminated

.        2x = 180      Divide both sides by 2 to isolate x

.          x = 90

Substitute x = 90 into one of the equations.

x + y = 100

90 + y = 100  Isolate y by subtracting 90 from both sides

y = 100 - 90

y = 10

Find xy = ?? by substituting y for 10 and x for 90.

xy = (90)(10) = 900

Therefore the value of ?? is 900.