Question

find the missing number in the equation collects on sunday.
$12 + 29 + 37 + \underline{17} = 90$

1. find the missing number that makes each equation true.

$18 - 10 = 9 - \underline{1}$
$35 + 30 = 45 + \underline{20}$

Explanation:

Step1: Calculate sum of known terms

$12 + 29 + 37 = 78$

Step2: Solve for missing number

$90 - 78 = 12$

Step3: Simplify left side of equation

$18 - 10 = 8$

Step4: Solve for missing number

$9 - 8 = 1$

Step5: Simplify left side of equation

$35 + 30 = 65$

Step6: Solve for missing number

$65 - 45 = 20$

Answer:

1. Missing number for $12 + 29 + 37 + \_\_ = 90$: 12
2. Missing number for $18 - 10 = 9 - \_\_$: 1
3. Missing number for $35 + 30 = 45 + \_\_$: 20