Бу — 7 = 7
3х — 8y = — 31

creo que es X= 13 , Y= -1

Step-by-step explanation:

3*(6y-7)-8y=-31

18y-21-8y=-31

10y=-10

y=(-1)

6*-1-7= x > X=13

b.) 160 miles on a 5 gallons car

step-by-step explanation:

240/10=24 miles/gallon

160/5=32 miles/gallon

30/1=30 miles/gallon

168/6= 28 miles/gallon

32 miles/gallon is the most amount, so this is the best.