Rose purchased 2 packs of red pens, 4 packs of black pens, and 3 packs of blue pens. the cost of each pack of pens was $2.50. the expression $2.50 • 2 + $2.50 • 4 + $2.50 • 3 represents the total cost of the pens. which expression also represents the total cost of the pens? a. $2.50 • 2 • 4 • 3 b. $2.50 • (2 + 4 + 3) c. $2.50 + (2 • 4 • 3) d. $2.50 + 2 + 4 + 3

each pack costs 2.5, she bought x packs

x=2+4+3=9

she bought 9 packs

so 2.5 times 9=22.50

she spend $22.50

B

Step-by-step explanation:

If she bought 9 packs of pens at 2.50$ each then she spent 22.50$ on pens. If you add up the packs and multiply by the price you get your answer. 2.50 * (2+3+4) = 22.50$

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