Answer:
John’s age is 8 years
Step-by-step explanation:
Let
x -----> John’s father's age
y -----> John’s age
z -----> John’s sister's age
we know that
-----> equation A
-----> equation B


-----> equation C
Substitute equation A and equation B in equation C and solve for y

Multiply by 2 both sides to remove the fraction



<em>Find the value of x</em>
<em>Find the value of z</em>

therefore
John’s father's age is 40 years
John’s age is 8 years
John’s sister's age is 4 years
Y could equal anything equal to or greater than 3. you can use 3, 4, 5, 6, 7 etc.
2x is the answer to that question it's simple math just
Answer:
c = 9
Step-by-step explanation:
-2c = -18
/-2 /-2 (Divide both sides by -2)
_______
c = 9