Question

Which expression will help make the following problem easier to solve using mental math? Arsha wants to buy 16 gallons of gasoline, which cost $2.10 per gallon.

16 • (2 + 0.1)

16(2) + 2(0.1)

2 • (16 + 0.1)

16(0.1) + 0.1(2)

i think its 16(0.1 + 0.1(2)

Answer 1

If you multiply 16(0.1)+0.1(2), you would get 1.6+.2=1.8 dollars which doesn't make sense since one gallon is $2.10.

So if Arsha wants to by 16 gallons then it would be 16(x), x for price of per gallon. So it would be 16(2.10), now since there is no option that has that, just manipulate where it still equals 16(2.10).

So for A, you have 16(2+0.1), if you add the insides, you would get 2.1 or 2.10. So that means its answer A.

Answer 2

ohh okay thank you mate

Answer 3

the idea is 2.10 can be written as (2+ 0.10)