Answer:
784 : 896
Step-by-step explanation:
sum the parts of the ratio
7 + 8 = 15 parts
divide the quantity by 15 to find the value of one part of the ratio
1680 ÷ 15 = 112 ← value of 1 part of the ratio, then
7 parts = 7 × 112 = 784
8 parts = 8 × 112 = 896
Thus 1680 in the ratio 7 : 8 = 784 : 896