Answer:
15. the x & y intercepts of an equations is zero
17. a + b =120
b=120 - a
a - b =140
a - (120 - a) = 140
2a - 120 = 140
2a = 260
a = 130
b = 120 - a
b = 120 - 130
b = -10
18.exponents when multiplying numbers with the same base, you subtract the exponents when dividing numbers with the same base. Any number to the power of zero equals 1, as long as the base number is not 0.
Explanation: