Answer:
Maryam is 18
Explanation:
sum the parts of the ratio , 4 + 6 + 7 + 3 = 20 parts
divide the sum of their ages to find the value of one part of the ratio.
60 years ÷ 20 = 3 years ← value of 1 part of the ratio
Naryam accounts for 6 parts, then
Maryam's age = 6 × 3 = 18