Answer:
the gcf for 40 and 42 is 2
and lcm for 40 and 42 is 840
Step-by-step explanation:
the factors of 40 are 1,2,4,5,8,10,20,40 ; the factors of 42 are 1,2,3,6,7,14,21,42 .
So what they have in common for GCF is 2 for a factor .
multiples of 40: 40, 80, 120,160,200,240,etc.
multiples of 42 : 42, 84,126,168,210,252,etc.
What they have in common for LCM is a multiple is 840
hope I helped ! please mark me brainlest if I got it right :)