Answer:
It was 6 7/8 pounds of fruit in the fruit salad.
Explanation:
Regina bought in total (in pounds) of fruit: B
![B=3(1)/(2)+4(3)/(4)\\ B=(3(2)+1)/(2)+(4(4)+3)/(4)\\ B=(6+1)/(2)+(16+3)/(4)\\ B=(7)/(2)+(19)/(4)\\ B=(7)/(2).1+(19)/(4)\\ B=(7)/(2).(2)/(2)+(19)/(4)\\ B=(7(2))/(2(2))+(19)/(4)\\ B=(14)/(4)+(19)/(4)\\ B=(14+19)/(4)\\ B=(33)/(4)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/rm8fmt5vhomuikjklml23gdlhpo4kvfa8t.png)
Regina bought in total 33/4 pounds of fruit
She used all (33/4 pounds) but 1 3/8 pounds of the fruit in a fruit salad, then she used in the fruit salad (in pounds): S
![S=B-1(3)/(8)\\ S=(33)/(4)-(1(8)+3)/(8)\\ S=(33)/(4)-(8+3)/(8)\\ S=(33)/(4)-(11)/(8)\\ S=(33)/(4).1-(11)/(8)\\ S=(33)/(4).(2)/(2)-(11)/(8)\\ S=(33(2))/(4(2))-(11)/(8)\\ S=(66)/(8)-(11)/(8)\\ S=(66-11)/(8)\\ S=(55)/(8)\\ S=(48+7)/(8)\\ S=(48)/(8)+(7)/(8)\\ S=6+(7)/(8)\\ S=6(7)/(8)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/gquohdbi4w9lsfs08vrs4cssnccrfht5n0.png)
It was 6 7/8 pounds of fruit in the fruit salad.