Please help me answer this question, ill give brainlist to anyone that helps me out. Im very confused. 11th grade Algebra 2

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

Which of the following would be a reasonable estimate for the weight of a pencil? a. 1 × 10^-20 lb b. 1 × 10^20 lb c. 1 × 10^2 lb d. 1 × 10^-2 lb

Ana’s dachshund weighed 5 5/8 pounds when it was born . by age 4 the dog weighed 6 times as much. fill each box with a number or symbols from the list to show how to find the weight of ana’s dog at age 4 . not all numbers and symbols my be used