Mary found 98 seashells and 34 starfishes on the beach. She gave Nancy some of her seashells. She has 39 seashells left. How many seashells did she give to Nancy?

She gave Nancy 59.

Step-by-step explanation:

98-39=59

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!