Answer:
392cm³
Step-by-step explanation:
First, we need to find what fraction of the whole volume was just added. We started with 4/7 and ended up with 3/4, so we can take the difference of the two to find the fractional part added:
[tex]\frac{3}{4}-\frac{4}{7} =\\\\\frac{21}{28}-\frac{16}{28} =\frac{5}{28}[/tex]
So, that 70cm³ represents 5/28 of the whole glass. If 70cm³ is 5/28 of the glass's volume, then 70/5 = 14cm³ must be 1/28 of the volume. From here, we can simply multiply 14 by 28 to find the total volume, all 28/28 of it:
14 · 28 = 392cm²
