D (7) should be the correct answer.
I will show you how to do the first one.....we are finding the GCF...the largest number that goes into each number (same for variables)
1.) 20yx , 80x³ ( factor each number and variable)
20 = 2, 4, 5, 10, 20
y = y
x = x
80 = 2, 4, 5, 8, 10, 16, 20, 40, 80
x³ = x, x, x
what is the largest number that 20 and 80 have in common? 20...
how about the variables? x
so, the Greatest Common Factor (GCF is 20x)
the answer is 60000 to the nearest 1000
