Answer:
D:3
Step-by-step explanation:
This is unit rate question
get unit rate by 252/6 = 42 so its $42 per unit bag
so 8 is 8 times $42 = $336
A set of equation can be set up:
a=b+15
3(a+b)=345
where a is the faster and b is the slower bus.
substitute b+15 into the second equation, so 6b+45=345, and 6b=300, therefore b=50.
we can then figure out that a=65