For two ratios to form a proportion they have to be equal.
To see if two ratios are equal we express them in their simplest form.
In this case we notice that in the first ratio both numbers are multiples of five, then:
In the second case we notice that both numbers are multiples of 2, then:
Since both ratios can be simplified to the same final ratio, they form a proportion.
Answer:
b. 2 cans of ink
Step-by-step explanation:
In order to calculate the number of cans you need to paint the complete wall, you first calculate the area of the wall by using the information about its width and height:
With one can you can paint 10m^2 of wall, with two cans you can paint 20m^2, which is enough to paint the wall of 12.5m^2.
Then, you need only two cans of ink
b. 2