Pls help! Looking for the missing length of n

The length of n is 40 ⇒ C

Step-by-step explanation:

The corresponding sides of the similar triangles are proportional, means have equal ratios

In the given figure

∵ The original triangle and its projection are similar

∴ Their corresponding sides have equal ratios

∴ =

→ By using the cross multiplication

∵ 15 × n = 30 × 20

∴ 15n = 600

→ Divide both sides by 15

∵ =

∴ n = 40

∴ The length of n is 40

b.) 160 miles on a 5 gallons car

step-by-step explanation:

240/10=24 miles/gallon

160/5=32 miles/gallon

30/1=30 miles/gallon

168/6= 28 miles/gallon

32 miles/gallon is the most amount, so this is the best.