Simplify this expression. 3x2(7x2 − 9)
a) 21x2 − 9
b) 21x2 − 27x2
c) 21x4 − 9
d) 21x4 − 27x2

Is the open sentence 5x-2=3x+2 true when x=2? justify your answer.

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

K-7/4=11 explanation: k-7 is the numerator and 4 is the denominator then right by it it just says = 11 ( i wish i knew how to do this but ummm i cant sis)