Distance/fuel=ratio
77.5/3.1 is proportional to xdistance/8.2
77.5/3.1=x/8.2
multiply both sides by (3.1*8.2)
635.5=3.1x
divide both sides by 3.1
205=x
205 miles
2. easy peasy
one way is
boys+15=girls
boys+girls=85
boys+boys+15=85
minus 15
2boys=70
divide 2
boys=35
Solve for x... multiply by 8.2 gallons on both sides (that cancels it on the right) side of the equation.
8.2 gallons * 77.5 miles / 3.1 gallons = x 635.5/ 3.1 = x 211.83 miles = x
Justin travels 211.83 miles on 8.2 gallons of gas
2) If we let boys = b, then girls has to be b + 15 (since there are 15 more girls than boys). Now together there are 85 members of the band so... boys + girls = 85 and since girls is b + 15, then...
b + b+15 = 85
Now solve for b. First combine like terms...
2b + 15 = 85
Now subtract 15 from each side (cancels the 15 on the left)
2b + 15 - 15 = 85 - 15 2b = 70
Now divide each side by 2 (cancels 2 on the left)
2b / 2 = 70 / 2 b = 35
So there are 35 boys in the band.
Just FYI, that also means there are 35+15 = 50 girls. Just so happens that 50 + 35 = 85 so our work checks!
