29+90

Solution (adapted for English, 7th grade understanding):

Problem: 29 + 90

Goal: understand the steps clearly

1. Break it into place values

• 29 has tens (2) and ones (9)
• 90 has tens (9) and ones (0)
• So we can add tens and ones separately: (2 + 9) tens and (9 + 0) ones

2. Add by decomposition

• 29 = 20 + 9
• 90 = 90
• Sum = (20 + 90) + 9 = 110 + 9 = 119

3. Column addition (check with standard method) 29

• 90

119

• Units: 9 + 0 = 9
• Tens: 2 + 9 = 11 → write 1 in tens place and carry 1 to the hundreds
• Result: 119

4. Quick mental math check

• Think of 29 as 30 − 1: 90 + 30 = 120; subtract 1 → 119

Answer: 119

If you’d like, I can also provide a Russian version or more practice problems with similar steps.