460 < 2x + 10 and 2x + 10 < 660
Solve x in each equation:
Rewrite so X is on the left side:
2x +10 >460
Subtract 10 from each side:
2x > 450
Divide both sides by 2:
x > 450 /2
x > 225
2x +10 <660
Subtract 10 from both sides:
2x < 650
Divide both sides by 2:
x < 650 / 2
x < 325
Combine the answer: 225 < x < 325
This means her carb intake needs to be more than 225 and less than 325 grams.
Wilda can do the job in 4 hours ... she does 1/4 (or 0.25) of it each hour.
Karla can do it in 5 hours ... she does 1/5 (or 0.2) of it each hour.
Wilda worked alone for 1 hour ... 0.25 of the job was done before her helper
arrived. So only 0.75 of the job remained to be done together.
Working together, they accomplish (0.25 + 0.2) = 0.45 of the job in 1 hour.
How many times do they need to do 0.45 of the job in order to finish
the 0.75 of it that remains ? That's the number of hours it will take them,
working together.
0.75 / 0.45 = <em>1 and 2/3</em>
After Wilda worked alone for 1 hour and Karla came along to join her, it will
take them another <em>1 hour and 40 minutes</em> to finish the job and go for a swim.
3x + 5y = 1 . . . . . . . . (1)
7x + 4y = -13 . . . . . . .(2)
(1) x 7: 21x + 35y = 7 . . (3)
(2) x 3: 21x + 12y = -39 .(4)
(3) - (4) = 23y = 46
y = 46/23 = 2
