請幫忙列式英數

1. 6 similar fountain pens costs $30x altogether. A ball pint pen is $5x/3 cheaper than each fountain pen.a. Find the cost of a ball pint pen in terms of x. The cost of a ball pint pen
= 30x/6 - 5x/3
= (30x-10x)/6
= 20x/6
= $10x/3
b. If a ball pint pen costs $12, find the cost of each fountain pen.10x/3 = 12
10x=36
x=3.6
Hence,the cost of each fountain pen
= 3.6(30)/6
= $18
2. Jenny has $6x more than May. May has $15 more than Lily. The three children have an average o $15x.a. How much money does Jenny have? Give your answer in term of x.
($ Jenny has + $ May has + $ Lily has)/3 = 15x
$Jenny has + ($Jenny has - 6x) +($Jenny has -6x-15)=45x
3$Jenny has = 45x+12x+15
$Jenny has = 19x+5
Hence, the amount of money Jenny has = $(19x+5)
b. If x=4 , how much money does they have altogether?The amount of money they have altogether= 15(4)*3= $1803. Leon had 6 P postcards. He used P
postcards, gave 6 postcards to his friend and shared the remaining
postcards. He used P postcards. Gave 6 postcards to his friend and
shared the remaining postcards equally with his 2 brothers. a. Express the number of postcards each had brother in terms of P.
The number of cards each brother had
= (6P-P-6)/2
= (5P-6)/2
= 5P/2 - 3
b. If P= 6, how many postcards did each brother have? Each brother had
=5(6)/3 - 3
= 30/3 - 3
= 10 - 3
= 7