A constant in an algebraic expression is defined as a term that does not change during the expression, so, in other words, a term that does not have a variable in it. so the constants are
12
-3.7
1/3
$7.9 cost of one pack
10 packs cost is $79
She pays $29 + Voucher
From the total $79 we substract the $29 she paid with cash or card.
79-29=50
So the value of the voucher is $50
PS: celia should cut on chocolate. Not healthy for her :)
2x-7=43
2x=50
x=25
I hope I helped you with your solution! If you could give me brainliest, I would be very thankful!