THERE ARE 4 QUESTIONS THEY ARE IN THE BOX THAT IS HIGHLIGHTED IT WILL BE HIGHLIGHTED AS 4A, 4B, 4C, AND THE LAST ONE SAY (D.)

it has to be a.

he spend 5.1 minutes chatting with his friends

step-by-step explanation:

2/5+1/2=9/10

6/1-9/10=5 1/10

c.

step-by-step explanation:

she should of added 9^2 and 12^2. that is because it is a^2+b^2=c^2. c^2 is the hypotenuse and should always be bigger than the other two numbers. which is why she should of added 9 squared and 12 squared together instead of 15 squared.