4th grade questions help!

Given abcd ac=38 and ae=3x+4 find the value of x

The center of the circumscribed circle lies on line segment and the longest side of the triangle is equal to the of the circle.

Kayla has a $500 budget for the school party. she paid $150 for the decorations. food will cost $5.50 per student. what inequality represents the number of students, s, that can attend the party?