Problem 1 : There are two numbers written on the board, which sum up to 27. The first number is 60% of the sum. What is the second number?

10.8

Step-by-step explanation:

Given that there are two numbers whose sum is equal to 27, you can set up an equation:

x + y = 27, where 'x' is the first number and 'y' is the second number

'The first number is 60% of the sum.' Set up another equation for the first number:

x = 27 (0.6) or x = 16.2

Since x = 16.2, plug this number into the first equation and solve for 'y':

16.2 + y = 27

y = 10.8