math/algebra
posted by allen on .
please check my answers
Suppose that the temperature outside is dropping at a constant rate. At noon, the temperature is 70 F and it drops to 58 F at 5 p.m. How much did the temperature change each hour?
12/5=2.4 degrees per hour.
Evaluate the expression if a=2, b=5,c=4, and d=6:4b+5dc/a
4b+5dc/a =
4(5)+5(6)(4)/(2)
4x5=20
5x6=30
4/2=2
answer= 20+30+2=52
Evaluate the expression if a=2, b=5,c=4, and d=6: 6^22bc+c^2
> 5²  2(5)(4) + (4)²
= 25 + 40 + 16
= 81
The simple interest I on a principle of P dollars at interest rate r for time t, in years, is given by I=Prt. Find the simple interest on a principle of $6000 at 3% for 2 years. (Hint: 3%=0.03)
Interest = 6000*.03*2
Simplify using the distributive property:7(4w3)25=
21+25w+28w=
21+3w
A triangle has sides 3x+7, 4x9, and 5x+6. Find the expression that represents the perimeter.
=3x + 7+ 4x  9+5x +6
=3x+4x+5x +79+6
=12x3
Simplify, if possible: 6x^2y^3+9x^2y^3/3x^2y^2

The temperature one is correct. You may want to include a negative sign to indicate that the temperature is dropping.
You made a sign mistake on the first evaluation. (You dropped one of your negative signs.)
On the second evaluation, you changed "6^2" to "5^2" in your work.
For the simple interest, you should multiply what you have to get a numerical answer in dollars.
Your distributive property problem is quite wrong. The distributive property states for an expression a(b+c), the answer will be ab + ac. Try to apply that to your problem.
On the perimeter, check 79+6. It's not 3. 
x+2y=3
3x+2y=1