Thank you for posting your question here at brainly. Below is the answer:
sum of Mc = 0 = -Ay(4.2 + 3cos(59)) + (275)(2.1 + 3cos(59)) + M
- Ay = (M + (275(2.1 + 3cos(59)))/(4.2 + 3cos(59))
sum of Ma = 0 = (-275)(2.1) - Cy(4.2 + 3cos(59)) + M
- Cy = (M - (2752.1))/(4.2 + 3cos(59))
Ay + Cy = 275 = ((M+1002.41)+(M-577.5))/(5.745)
= (2M + 424.91)/(5.745)
M = ((275*5.745) - 424.91)/2
= 577.483 which rounds off to 577
Is it maybe supposed to be Ay - Cy = 275