The sum of 4 times a number and six times a number is 36. the difference of five times the second number and three times the first number is 49. find the numbers

4x + 6y = 36...reduce2x + 3y = 18
5y - 3x = 49...rearrange...-3x + 5y = 49

2x + 3y = 18 ...multiply by 3
-3x + 5y = 49 ..multiply by 2

6x + 9y = 54 (result of multiplying by 3)
-6x + 10y = 98 (result of multiplying by 2)
add
19y = 152
y = 152/19
y = 8

2x + 3y = 18
2x + 3(8) = 18
2x + 24 = 18
2x = 18 - 24
2x = - 6
x = -6/2
x = -3

first number is -3, second number is 8

Well if you have 20 bats you probably want 20 balls? you don’t have enough context to answer the question.