Step-by-step explanation:
1.
so 90 km on 17 liters.
that is a 90/17 ratio (or proportion).
that means it runs 90/17 km on 1 liter.
and therefore (90/17)×20 on 20 liters.
90×20/17 = 105.8823529... km
2.
the ratio is 66/22 based on the RPMs.
66/22 = 3/1 = 3
so, the larger gear has then 3×6 = 18 teeth.
3.
the ratio is 150/75 based on the RPMs.
the circumference of a circle is
2×pi×r
so, it is a linear relationship with the radius r (and therefore the diameter d).
so, the diameter of the larger pulley is 2×10 = 20 in
4.
the ratio here is 18/6.
18/6 = 3/1 = 3.
again, this relates to the circumference, which is a linear relationship with the radius or diameter.
the smaller gear has then 72/3 = 24 teeth.
5.
the ratio is 2/3.
so, the larger pulley has 3450×2/3 RPM.
= 2,300 RPM
6.
2.5 kg cost 110.
that is a 2.5/110 ratio :
and that means we get 2.5/110 kg for one unit of money.
and therefore we get 80 × 2.5/110 kg for 80 units of money.
80 × 2.5/110 = 8 × 2.5/11 = 20/11 = 1.818181818... kg
