Question

the sum of 2 number is 20 their lcm is 42 and hcf is 2 the numbers are

Answer 1

Let the numbers be x & y.
given:
x+y=20
xy =hcf × lcm
xy=2×42
xy=84
After prime factorisation we get
xy=84=12×7
x=12 ;y=7
when x=12
12+y=20
y=8
when y=7
x+7=20
x=13
number are 13 and 8