How do I solve 3x-y=15

How many grams must be adde to 970g to make 1 and a half kg

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?

Which graph represents the same relation is the sa which graph represents the same relation as the set {(-3-2)}