50 POINTS TO WHOEVER HELPS WITH THIS I NEED IT ASAP PLEASE HELP

4a ) Difference ⇒ $ 63.24,

4b ) 4 children

Step-by-step explanation:

4a ) If the number of children is represented by the value of x, let us substitute a family of 2 children as value of x into this equation we are given;

y = 21.08 * ( 2 ) + 85.15 ⇒ Multiply 21.08 by 2,

y = 42.16 + 85.15 ⇒ Combine like terms,

y = 127.31

If y ⇒ amount spent on grocery's, let us solve for the amount spent on 5 children, and subtract from this amount;

y = 21.08 * ( 5 ) + 85.15 ⇒ Multiply 21.08 by 5,

y = 105.4 + 85.15 ⇒ Combine like terms,

y = 190.55

Difference; 190.55 - 127.31 = 63.24,

Solution; Difference ⇒ $ 63.24

4b ) If the amount is $ 169.47, let us plug it into our given equation provided amount spent on groceries ⇒ y;

169.47 = 21.08x + 85.15 ⇒ Subtract 85.15 from either side of equation,

21.08x = 84.32 ⇒ Divide either side 21.08,

x = 4 children

Solution; 4 children