A clothing store is having a sale on shirts and jeans. Four shirts and two pairs of jeans cost $78. Three shirts and five pairs of jeans cost $111. The system of equations 4s + 2j = 78
3s + 5j = 111
models this situation, where s is the cost of a shirt and j is the cost of a pair of jeans. How much does one shirt and one pair of jeans cost?

One shirt is $12 and one pair of jeans is $15

Step-by-step explanation:

Solve by elimination by multiplying the top equation by 3 and the bottom equation by -4:

12s + 6j = 234

-12s - 20j = -444

Add these together, and solve for j:

-14j = -210

j = 15

So, a pair of jeans is $15. Plug in 15 as j into one of the equations and solve for s:

3s + 5j = 111

3s + 5(15) = 111

3s + 75 = 111

3s = 36

s = 12

One shirt is $12 and one pair of jeans is $15.

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

answer: what are the answer choices?

step-by-step explanation: