What is the least common multiple 20 28

140

Step-by-step explanation:

First, list the prime factors of both 20 and 28. Then, multiply each factor the greatest number of times it occurs in both 20 and 28. If the same factor occurs more than once for both 20 and 28, multiply the factor the greatest number of times it occurs

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18