The purpose of this study was to explore and compare the proficiency of Grade 11 Mathematics and Mathematical Literacy (ML) learners in solving two problems based on the temperature conversion formula. The first was a result-unknown problem that asks for the result of a formula for a given input. The second was a start-unknown problem in which the result of a formula is presented and the input is required. The sample for the study was 94 Mathematics and 339 ML Grade 11 learners from four rural schools in North Durban. The results indicate that 80% of the Mathematics group and 76% of the ML group solved the result-unknown problem while 32% of the Mathematics group and 7% of the ML group solved the start-unknown version. The findings reveal that the vast majority of the ML learners and most of the Mathematics learners did not have the requisite algebraic skill to manipulate the formula in order to arrive at a solution. Instead, more than half of the alternative solution strategies are classified as "number grabbing" and "swopping variables". It is recommended that interventions to improve learners' algebraic proficiency should be targeted at lower grades.