Let "x" be the C's capital (the value under the question). Then you have this equation (proportion) from the condition= , (1) or, equivalently = . Cross-multiply and then simplify and solve for x: 7x = 3*(5000+25000+x) 7x = 90000 + 3x 4x = 90000 ====> x = = 22500. ANSWER CHECK. Substitute the found value of x into equation (1) = = = . ! Correct !