Question

Solve system of equations

At McDonalds, a packet of ranch dressing has 10 more calories than eight side salads. Three side salads and two packets of ranch dressing have a total of 400 calories. How many calories are in each item?

Answer 1

R = 8S +10
3S + 2R = 400
Substitute first formula into second formula
3S + 2(8S +10) = 400
3S + 16S + 20 = 400
19S +20 =400
19S + 20 -20 = 400 – 20
19S = 380
19S / 19 = 380/19
S = 20
Plug 20 into first formula
R = 8(20) +10
R = 160+10
R= 170
Side Salads are 20 calories and Ranch Dressing is 170 calories.