It looks like the given equation is
234₅ + 434₅ + x₅ = 2304₅
First, we have
234₅ + 434₅ = 1223₅
because
• 4₅ + 4₅ = (8)₅ = (5 + 3)₅ = 10₅ + 3₅ = 13₅
(carry the 1)
• 3₅ + 3₅ + 1₅ = (7)₅ = (5 + 2)₅ = 10₅ + 2₅ = 12₅
(carry the 1)
• 2₅ + 4₅ + 1₅ = (7)₅ = (5 + 2)₅ + 10₅ + 2₅ = 12₅
Then x₅ = 2304₅ - 1223₅. We have
• 4₅ - 3₅ = 1₅
0₅ - 2₅ is negative, so we borrow a 1 from the next digits place,
• 10₅ - 2₅ = (5)₅ - 2₅ = 3₅
• (3 - 1)₅ - 2₅ = 2₅ - 2₅ = 0₅
• 2₅ - 1₅ = 1₅
x₅ = 2304₅ - 1223₅ = 1031₅