Answer:  98 + 72w ≥ 530
Explanation:
Hi, to answer this question we have to write an inequality with the information given: 
She earns $78 per week (w) babysitting, and she already has $98 in savings. 
Mathematically speaking: 
78w +98 
Where w is the number of weeks. 
Since the snowboard costs $530, the expression 78w +98 must be greater or equal than 530. 
98 + 72w ≥ 530 
Solving:
72w ≥ 530 -98
72w ≥ 432
w ≥ 432/72
w ≥ 6
She needs to babysit at least 6 weeks to buy the snowboard.
Feel free to ask for more if needed or if you did not understand something.