Answer: 5(1st+8t)
Step-by-step explanation:You factor 5st + 40t using GCF .And the GCF of 5 and 40 is 5 .So you take 5st and you divide it by 5 and also you take 40 t and divide it by 5 too.And after you take 5st and you divide it by 5 ,you get 1 st .To add on,after you take 40 t and divide it by 5 you get 8t .Finally ,you take the GCF which is 5 and place Parentheses next to it and you take 1st and 8t and you add them together .
So your expression that is equivalent to 5st + 40t ,is 5(1st+8t) .
Hope it help :)and You are welcome .