If (x + y)/(ax + by) = (y + z)/(ay + bz) = (z + x)/(az + bx), prove that each of these ratio is equal to (2)/(a + b), unless x + y + z = 0.

We know that if , then each ratio Hence, proved that,

The ratio of 4 litres to 900 mL is
4 : 9
40 : 9
9 : 40
20 : 9

When the number 210 is increased in the ratio 5 : 7, the new number is
150
180
294
420