The cost of new truck is $ 20000
Solution:
Given that Sally decided to look at new and used trucks
Sally found a used truck for $15,000 Sally found that she paid 75% of the price of a new truck
To find: cost of new truck
Let "x" be the cost of new truck
From given statement,
cost of used truck = $ 15,000
She paid 75% of the price of a new truck, means that $ 15,000 is equal to 75 % of cost of new truck
Therefore,
75 % of cost of new truck = $ 15000
75 % of x = 15000

Thus cost of new truck is $ 20000