Jennifer and Callie are training for a marathon. Jennifer has run m miles, and Callie has run 3 times as many as Jennifer. The expression shows how many miles they have run altogether. m + 3m

i found two solutions,   n = 2 • ± √3 = ± 3.4641

step-by-step explanation:

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