Question

Jerry is making 2 kinds of cakes. One needs 18/20 cup of flour and the other needs 3/8. Estimate how much flour he needs

Answer 1

bearing in mind that the LCD in this case for those two denominators is 40, so let's use that for the sum

`\bf \cfrac{18}{20}+\cfrac{3}{8}\implies \stackrel{\textit{using the LCD of 40}}{\cfrac{(2)18+(5)3}{40}}\implies \cfrac{36+15}{40}\implies \cfrac{51}{40}\implies 1(11)/(40)`