Write a problem for the equation x-5=2

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

If a flying disk is 139 meters in the air and travels at an average of 13 m/s how long is it in the air

In the diagram below, abc is congruent to dec what is the value of x