英和和英

a complex problem

a complicated problem

a complicated problem

a bewilderingly complex problem

solve a difficult problem

too facile a solution for so complex a problem

a problem that is difficult to solve

solve problems

a solution of the difficulty―a way out （of the difficulty）

a way out （of the difficulty）

a solution to a serious problem

Resolve an issue

a complicated problem that is difficult to solve

It is an intricate problem.

a solution of the puzzle

to solve problem

an intricate problem

to solve a difficulty

an ingenious solution to the problem

to solve a hard problem―cut the Gordian knot

remediable problems

solve a problem

solve a problem

the key to (solving) a problem

to have difficulty in solving a troublesome problem

the way of solving a problem

deal with a difficult problem

to solve a problem

of a problem, to be solved

a problem and the solution thereof