Answer:
Shorter piece length is 18 inches
Step-by-step explanation:
Let's marked first piece with x and second with y
x + y = 42
Given ratio is x : y = 3 : 4
From this proportion we get
x = 3 c and y = 4 c where c is coefficient of proportionality
when we replace this in initial equation we get
3 c + 4 c = 42 => 7 c = 42 => c = 42/7 = 6 c = 6
x = 3 · 6 = 18 inches and z = 4 · 6 = 24 inches
shorter piece is x = 18 inches
God with you!!!