Final answer:
Greg wrote x symbols, Dina wrote one more symbol, Vivian wrote one more symbol than Dina, and Yuri wrote one more symbol than Vivian. The sum of the symbols written by all four students is x + (x + 1) + (x + 2) + (x + 3) = 142. Vivian wrote 36 symbols.
Step-by-step explanation:
Let's solve this problem step by step:
Let's assume that Greg wrote x symbols.
Dina wrote one more symbol than Greg, so she wrote the x + 1 symbol.
Vivian wrote one more symbol than Dina, so she wrote (x + 1) + 1 symbol = x + 2 symbols.
Yuri wrote one more symbol than Vivian, so he wrote (x + 2) + 1 symbol = x + 3 symbols.
The teacher made them wash 142 symbols off the desk.
So, the sum of the symbols written by all four students is:
x + (x + 1) + (x + 2) + (x + 3) = 142
Combining like terms:
4x + 6 = 142
Subtracting 6 from both sides:
4x = 136
Dividing both sides by 4:
x = 34
Vivian wrote x + 2 symbols, which is 34 + 2 = 36 symbols.