A submarine at -144 meters dives to a depth 6 times its original depth. What depth does the submarine dive?

Abike shop sells you a bicycle for $63 and a helmet for $21. the total cost is 150% of what the shop spent originally. how much did the shop spend originally? how much profit did the bike shop earn by selling the bicycle and helmet to you ?

Ineed i been stuck on this question since yesterday

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?