Secants from the same point have the same product of length to the near intersection times length to the far intersection from the point.
1) 5(5+x) = 6(6+4)
... 25 + 5x = 60 . . . . eliminate parentheses using the distributive property
... 5x = 35 . . . . . . . . subtract 25
... x = 7 . . . . . . . . . . . divide by 5
2) The same rule applies.
... 3(3+5) = 4(4+x)
... 24 = 16 + 4x . . . . . eliminate parentheses
... 8 = 4x . . . . . . . . . . . subtract 16
... 2 = x . . . . . . . . . . . . divide by 4