Patty went to visit her cousins for the weekend. She drove 260 km in 2 h 45 min, some of it on a 100 km/h highway and the rest on 80 km/h roads.
MUST BE SYSTEM OF EQUATIONS
f = 100 kph distance , s = 80 kph distance
f + s = 260 km
f/100 + s/80 = 2.75 ... multiplying by 100 ... f + 1.25 s = 275
subtracting equations (to eliminate f) ... .25 s = 15
solve for s , then substitute back to find f