N*(21/100)=(700/100)
n=(700/100)/(21/100)
n=(700/100)*(100/21)
n=700/21
n=33+1/3
So <em><u>thirty three</u></em> $0.21 pencils can be purchased for $7.00.
So, how much acid is there in 6 gallons? well is 20% acid or (20/100), so the amount of acid in it just (20/100) * 6 or 1.2, the rest is say water.
now, if we want a 90% solution, and say we add "y" gallons, how much acid is in it? well (90/100) * y, or 0.9y.
now let's add "x" gallons of pure acid, now, pure acid is just pure acid, so is 100% acid, how much acid is there in it? (100/100) * x, or 1x or just x.
we know whatever "x" and "y" amounts are, they -> x + 6 = y
and we also know that x + 1.2 = 0.9y
Answer:

Step-by-step explanation:
So we have the system:

If we isolate the x-variable in the first equation:

Subtract 2y from both sides:

Divide both sides by -1:

Therefore, we would substitute the above into the second equation:

The answer is 2y+6
Further notes:
To solve for the system, distribute:

Simplify:

Subtract:

Divide:

Now, substitute this value back into the isolated equation:

Answer:
wala sa choices ang sagot.
ANS: 128
EXPLANATION
a(9)=14+2(9-1)
a(9)=14+2(8)
a(9)=16(8)
9= 128
yan sagot ko po