450:(18-y:7)=50

To solve the equation 450:(18-y:7) = 50, we first need to simplify the expression by resolving the division before proceeding with other operations.

450:(18-y:7) can be rewritten as 450 ÷ (18 - y/7), which is the same as (450)/(18 - y/7) = 50.

Now, for the next step, we can rewrite the equation as (450)/(18 - y/7) = 50. To solve this equation, we must isolate the variable y by cross multiplying.

Therefore, we have 450 = 50(18 - y/7). Continuing the calculation, we simplify as 450 = 900 - 50y/7.

Subsequently, by subtracting 900 from both sides, we obtain -450 = -50y/7. Multiplying by -7 to isolate y, we find that y = 450 / 50.

Finally, we compute y = 9.

The solution to the equation 450:(18-y:7) = 50 is y = 9.