Taking into account the rule of three, she will need 5.6 cups of sugar to maintain the ratio.
Rule of three
In first place, the rule of three is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them.
That is, what is intended with it is to find the fourth term of a proportion knowing the other three.
If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other) , the direct rule of three must be applied.
To solve a direct rule of three, the following formula must be followed, being a, b and c known data and x the variable to be calculated:
a ⇒ b
c ⇒ x
So: x= (c×b)÷a
Cups of sugar
In this case, you can apply the following rule of three: if a chocolate chip cookie recipe calls for 2.5 cups of chocolate chips for every 2 cups of sugar, 7 cups of chocolate chips need how many cups of sugar?
cups of sugar= (7 cups of chocolate chips×2 cups of sugar)÷2.5 cups of chocolate chips
cups of sugar= 5.6 cups of sugar
Finally, she will need 5.6 cups of sugar to maintain the ratio.