2 Peter bought some packets of sweets from a shop. Each packet of sweets cost $2.
For every two packets of sweets that he bought, he was given one packet free. If he
left the shop with a total of 31 packets of sweets, find
(a) the number of packets of sweets given free.
(1)

21 packets bought, 10 packets free

Step-by-step explanation:

to find the total number of combinations, multiply the quantity of each item by each other:

2 pairs of shoes x 3 pairs of shorts = 6 different combinations.

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!