The difference of a number n and the number 8 is 42

With this question substitute t=3 and t=5 to determine if the two expressions are equivalent. 4(t + 3) 4t+12 which statements are true? check all that apply. a. the value of both expressions when t =5 is 32. b. the two expressions are not equivalent. c. the value of both expressions when t=3 is 15. d. the value of both expressions when t=5 is 23. e. the two expressions are equivalent. f. the value of both expressions when t=3 is 24.

I'm confused on this could anyone me and show me what i need to do to solve it.

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of