Answer:
1. x = 42
2. y = 46
3. z = 0
Explanation:
1. 45 + x = 87
subtract 45 from both sides
x = 42
2. y - 31 = 15
add 31 to both sides
y = 46
3. 5z = 0
divide 5 from both sides
z = 0/5
since any fraction with a numerator of 0 is equal to 0, we get
z = 0