It depends on what score of Quant you're looking for. If you're seeking for 40+ then I don't think you can get over without learning the basic Algebra.
Backsolving and picking numbers may work for some questions, especially easy and/or medium difficulty bins; but for harder questions, you'll have to know algebric manipulations as questions will not neccessarily contain numebers.
Algebra is involved in number properties/comb & perm/stats/ geometry and all sorts of math topics.