L := 35; k := .1990625; R := 0.4e-2; r0 := .1;
eq7 := Dmax+deltaH+.5 = 6.76;
eq8 := R*L^2/(4*k)-2*de*deltaH-deltaH^2 = 0;
eq6 := L/(8*((L-1.4*Dmax)^2/(8*Dmax*L)+ln(.7*Dmax/r0)/Pi));
solve({eq6, eq7, eq8}, {Dmax, de, deltaH});
Warning, solutions may have been lost
 

I entered these equations but maple will not solve it. What do I do wrong?