Please help me with this.

7.9315

Step-by-step explanation:

1.no =7/3±85/16±2/7

=2665/336

=7.9315

2no =86/9-17/5

=227/45

=6.15556

3no= 45/7×53/4

=2385/28

=85.1785

4no=67/4÷5/2

=67/4×2/5

=134/20

=67/10

=6.7

1)  first step

in this exercise you must establish a relation of proportion

if a staghorn coral can add as  0,67 foot per year then in 5 years  can grow X

0,67 foot 1 year

    X 5 years  

X = 5 × O,67/ 1 = 3,35 ,  a staghorn coral can grow 3,35 foot in 5 years