math
posted by mary .
In the following, write an expression in terms of the
given variables that represents the indicated quantity:
a. The cost of having a plumber spend h hr at your
house if the plumber charges $30 for coming to the
house and $x per hour for labor
b. The amount of money in cents in a jar containing
some nickels and d dimes and some quarters if there
are 4 times as many nickels as dimes and twice as many
quarters as nickels
c. The sum of three consecutive integers if the greatest
integer is x

cost: 30 + x*h
money: 10d + 5*4d + 25(2*4d)) = 230d
sum: x2 + x1 + x = 3x3 
a. Cost = $30.00 + h x $x
$30 initial fee plus number of hours times the cost per hour.
b. The value of the dimes can be written as $0.10 x d (the number of dimes). The number of nickels can be written as 4 times the number of dimes (4d) but the value is written as $0.05 x 4d. The number of quarters is twice the number of nickels which is four times the number of dimes. So, the number of quarters is (8d). The value of the quarters is $0.25 x 8d.
The equation would be: ($0.10 x d) + ($0.05 x 4d) + ($0.25 x 8d)=$_____. You could, then factor out the d (number of dimes), multiply the values($0.10, $0.05 and $0.25) times their respective quantity multiplier (1, 2, 4). This gives you the amount = $2.30 x d (for every one dime, you have enough dimes, nickels, and quarters to equal $2.30, so count the dimes and multiply by $2.30.
c. Sum = x + (x1) + (x2)= 3x3