The best answer would be D
How much part can sally paint in an hour ?
a ÷ 7 = a/7
And what about Steve ?
a ÷ 9 = a/9
Where, a is the total area of the room.
So, let the time taken by both of them to paint the room together be 't'
So,
t(a/7 + a/9) = a
t(9a/63 + 7a/63) = a
t(16a/63) = a
t = 63/16 ≈ 4 hr
The answer to the question in the photo is 21
Answer:
90% Solution
Step-by-step explanation:
5% of 90 + 90% of x = 75% of (90 + x)
5×90/100 + 90x/100 = 75×90/100 + 75x/100
Or 90x/100 - 75x/100 = 75×90/100 - 5×90/100
Or 15x/100 = 90×70/100
Or X = 420ml
You Will Need ML Of The 90% Solution To Obtain ML Of The Desired 75% Solution.
Isolate this variable, <em>x</em>,<em> </em>by dividing each side by factors that do <em>not</em> contain the variable.
